The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform

Zhenping Feng - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Investigations of the Long Blade Performance Using RANS Solution and FEA Method Coupled With One-Way and Two-Way Fluid-Structure Interaction Models
    Volume 2: I&C Digital Controls and Influence of Human Factors; Plant Construction Issues and Supply Chain Management; Plant Operations Maintenance Agi, 2017
    Co-Authors: Minyan Yin, Liming Song, Zhenping Feng
    Abstract:

    The aerodynamic and mechanical performance of the last stage was numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS) solution and Finite Element Analysis (FEA) coupled with the one-way and two-way fluid-structure interaction models in this work. The part-Span damping snubber and tip damping shroud of the rotor Blade and aerodynamic pressure on rotor Blade mechanical performance was considered in the one-way model. The two-way fluid-structure interaction model coupled with the mesh deformation technology was conducted to analyze the aerodynamic and mechanical performance of the last stage rotor Blade. One-way fluid-structure interaction model numerical results show that the location of nodal maximum displacement moves from leading edge of 85% Blade Span to the trailing edge of 85% Blade Span. The position of nodal maximum Von Mises stress is still located at the first tooth upper surface near the leading edge at the Blade root of pressure side. The two-way fluid-structure interaction model results show that the variation of static pressure distribution on long Blade surface is mostly concentrated at upper region, absolute outflow angle of long Blade between the 40% Span and 95% Span reduces, the location of nodal maximum displacement appears at the trailing edge of 85% Blade Span. Furthermore, the position of nodal maximum Von Mises stress remains the same and the value decreases compared to the oneway fluid-structure model results.

  • Unsteady Analysis on the Effects of Tip Clearance Height on Hot Streak Migration Across Rotor Blade Tip Clearance
    Journal of Engineering for Gas Turbines and Power, 2014
    Co-Authors: Zhaofang Liu, Zhao Liu, Zhenping Feng
    Abstract:

    This paper presents an investigation on the hot streak migration across rotor Blade tip clearance in a high pressure gas turbine with different tip clearance heights. The Blade geometry is taken from the first stage of GE-E3 turbine engine. Three tip clearances, 1.0%, 1.5% and 2.5% of the Blade Span with a flat tip were investigated respectively, and the uniform and non-uniform inlet temperature profiles were taken as the inlet boundary conditions. By solving the unsteady compressible Reynolds-averaged Navier-Stokes equations, the time dependent solutions were obtained. The results indicate that the large tip clearance intensifies the leakage flow, increases the hot streak migration rate, and aggravates the heat transfer environment on Blade tip. However, the reverse secondary flow dominated by the relative motion of casing is insensitive to the change of tip clearance height. Attributed to the high-speed rotation of rotor Blade and the low pressure difference between both sides of Blade, a reverse leakage flow zone emerges over Blade tip near trailing edge. To eliminate the effects of Blade profile variation due to twist along the Blade Span on the aerothermal performance in tip clearance, the tested rotor (straight) Blade and the original rotor (twisted) Blade of GE-E3 first stage with the same tip profile are compared in this paper.Copyright © 2013 by ASME

  • Unsteady Analysis on the Effects of Tip Clearance Height on Hot Streak Migration Across Rotor Blade Tip Clearance
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Zhaofang Liu, Zhao Liu, Zhenping Feng
    Abstract:

    This paper presents an investigation on the hot streak migration across rotor Blade tip clearance in a high pressure gas turbine with different tip clearance heights. The Blade geometry is taken from the first stage of GE-E3 turbine engine. Three tip clearances, 1.0%, 1.5% and 2.5% of the Blade Span with a flat tip were investigated respectively, and the uniform and non-uniform inlet temperature profiles were taken as the inlet boundary conditions. By solving the unsteady compressible Reynolds-averaged Navier-Stokes equations, the time dependent solutions were obtained. The results indicate that the large tip clearance intensifies the leakage flow, increases the hot streak migration rate, and aggravates the heat transfer environment on Blade tip. However, the reverse secondary flow dominated by the relative motion of casing is insensitive to the change of tip clearance height. Attributed to the high-speed rotation of rotor Blade and the low pressure difference between both sides of Blade, a reverse leakage flow zone emerges over Blade tip near trailing edge. To eliminate the effects of Blade profile variation due to twist along the Blade Span on the aerothermal performance in tip clearance, the tested rotor (straight) Blade and the original rotor (twisted) Blade of GE-E3 first stage with the same tip profile are compared in this paper.

  • Tip Leakage Flow and Heat Transfer Predictions for Turbine Blades
    Volume 4: Turbo Expo 2007 Parts A and B, 2007
    Co-Authors: Dianliang Yang, Zhenping Feng
    Abstract:

    A numerical study was performed to simulate the tip leakage flow and heat transfer on the first stage rotor Blade in GE-E3 engines. Calculations were performed for both flat and squealer Blade tips by means of solving Reynolds-averaged N-S equations in conjunction with the k-ω two-equation turbulence model. For squealer tip Blades, several cases were considered with five different tip gap-Blade Span ratios of 0.4%, 0.7%, 1.0%, 1.3%, and 1.6%, and four different groove depth-Blade Span ratios of 1%, 2%, 3%, and 4%. A linear experimental cascade was calculated first to validate this turbulence model, and the results show good agreement with that of the experiment. With the results of several cases discussed and compared, flow structure and heat transfer characteristics in the tip gap are illustrated. The effects of the tip gap and groove depth on flow and heat transfer are significant. The leakage flow is weakened by deepening the tip groove. However, when the groove depth is larger than 3% of the Blade Span, no further leakage flow reduction will occur. The average heat transfer rate on the tip surface reduces as groove depth increases. An increase in tip gap height will increase the leakage flow, and thus lead to an increase in average heat transfer rate on the tip surface.Copyright © 2007 by ASME

John B Niemczuk - One of the best experts on this subject based on the ideXlab platform.

  • Blade vortex interaction noise reduction with active twist smart rotor technology
    Smart Materials and Structures, 2001
    Co-Authors: Peter C Chen, Robert A D Evans, James D. Baeder, John B Niemczuk
    Abstract:

    The results of this analytical feasibility study suggest that active Blade twist technology is a viable means to reduce Blade-vortex interaction (BVI) noise in rotorcraft systems. A linearized unsteady aerodynamics analysis was formulated and successfully validated with computation fluid dynamics (CFD) analysis. A simple control scheme with three control points was found to be effective for active BVI noise reduction. Based on current-day actuation technology where one to two degrees of twist per Blade activation Span is expected, measurable noise reductions of 2-4 dB were predicted for the relatively strong, close vortex interactions. For weaker vortex interactions, reductions of 7-10 dB were predicted. The required twist actuation per Blade Span for complete unsteady loading cancellation, however, may be infeasible because of the large stroke and high-frequency activation requirements.

  • Active twist smart rotor technology for Blade-vortex interaction noise reduction
    Smart Structures and Materials 1999: Smart Structures and Integrated Systems, 1999
    Co-Authors: Peter C Chen, Robert A D Evans, John B Niemczuk, James D. Baeder, Paul Ross
    Abstract:

    The results of this feasibility study suggest that active Blade twist technology is a viable means to reduce Blade- vortex interaction (BVI) noise in rotorcraft systems. A linearized unsteady aerodynamics analysis was formulated and successfully validated with computation fluid dynamics analysis. A simple control scheme with three control points was found to be effective for active BVI noise reduction. Based on current-day actuation technology where 1 to 2 degrees of twist per Blade activation Span is expected, measurable noise reductions of 2 to 4 dB were predicted for the relatively strong, close vortex interactions. For weaker vortex interactions, reductions of 7 to 10 dB were predicted. The required twist actuation per Blade Span for complete unsteady loading cancellation, however, may be infeasible because of the large stroke and high frequency activation requirements.

Peter C Chen - One of the best experts on this subject based on the ideXlab platform.

  • Blade vortex interaction noise reduction with active twist smart rotor technology
    Smart Materials and Structures, 2001
    Co-Authors: Peter C Chen, Robert A D Evans, James D. Baeder, John B Niemczuk
    Abstract:

    The results of this analytical feasibility study suggest that active Blade twist technology is a viable means to reduce Blade-vortex interaction (BVI) noise in rotorcraft systems. A linearized unsteady aerodynamics analysis was formulated and successfully validated with computation fluid dynamics (CFD) analysis. A simple control scheme with three control points was found to be effective for active BVI noise reduction. Based on current-day actuation technology where one to two degrees of twist per Blade activation Span is expected, measurable noise reductions of 2-4 dB were predicted for the relatively strong, close vortex interactions. For weaker vortex interactions, reductions of 7-10 dB were predicted. The required twist actuation per Blade Span for complete unsteady loading cancellation, however, may be infeasible because of the large stroke and high-frequency activation requirements.

  • Active twist smart rotor technology for Blade-vortex interaction noise reduction
    Smart Structures and Materials 1999: Smart Structures and Integrated Systems, 1999
    Co-Authors: Peter C Chen, Robert A D Evans, John B Niemczuk, James D. Baeder, Paul Ross
    Abstract:

    The results of this feasibility study suggest that active Blade twist technology is a viable means to reduce Blade- vortex interaction (BVI) noise in rotorcraft systems. A linearized unsteady aerodynamics analysis was formulated and successfully validated with computation fluid dynamics analysis. A simple control scheme with three control points was found to be effective for active BVI noise reduction. Based on current-day actuation technology where 1 to 2 degrees of twist per Blade activation Span is expected, measurable noise reductions of 2 to 4 dB were predicted for the relatively strong, close vortex interactions. For weaker vortex interactions, reductions of 7 to 10 dB were predicted. The required twist actuation per Blade Span for complete unsteady loading cancellation, however, may be infeasible because of the large stroke and high frequency activation requirements.

  • Feasibility study to build a smart rotor: induced-strain actuation of airfoil twisting using piezoceramic crystals
    Smart Structures and Materials 1993: Smart Structures and Intelligent Systems, 1993
    Co-Authors: Peter C Chen, Inderjit Chopra
    Abstract:

    The objective of this research is to develop a dynamically-scaled helicopter rotor Blade with embedded piezoceramic elements as sensors and actuators to control Blade vibrations. A 6 ft diameter 2-Bladed Froude-scale bearingless rotor model is built where each Blade is embedded with banks of specially-shaped piezoelectric crystals at +/- 45 degree angles on the top and bottom surfaces. A twist distribution along the Blade Span is achieved through in-phase excitation of the top and bottom crystals at equal potentials. The non-rotating static torsional response of the piezoceramic Blade is experimentally determined and then correlated with the prediction by theory.

Chander Prakash - One of the best experts on this subject based on the ideXlab platform.

  • Effect of Tip Gap and Squealer Geometry on Detailed Heat Transfer Measurements Over a High Pressure Turbine Rotor Blade Tip
    Journal of Turbomachinery, 2004
    Co-Authors: Hasan Nasir, Srinath V. Ekkad, Ronald Scott Bunker, David Kontrovitz, Chander Prakash
    Abstract:

    The present study explores the effects of gap height and tip geometry on heat transfer distribution over the tip surface of a HPT first-stage rotor Blade. The pressure ratio (inlet total pressure to exit static pressure for the cascade) used was 1.2, and the experiments were run in a blow-down test rig with a four-Blade linear cascade. A transient liquid crystal technique was used to obtain the tip heat transfer distributions. Pressure measurements were made on the Blade surface and on the shroud for different tip geometries and tip gaps to characterize the leakage flow and understand the heat transfer distributions. Two different tip gap-to-Blade Span ratios of 1% and 2.6% are investigated for a plane tip, and a deep squealer with depth-to-Blade Span ratio of 0.0416. For a shallow squealer with depth-to-Blade Span ratio of 0.0104, only 1% gap-to-Span ratio is considered. The presence of the squealer alters the tip gap flow field significantly and produces lower overall heat transfer coefficients. The effects of different partial squealer arrangements are also investigated for the shallow squealer depth. These simulate partial burning off of the squealer in real turbine Blades. Results show that some partial burning of squealers may be beneficial in terms of overall reduction in heat transfer coefficients over the tip surface.

  • effects of tip gap film injection from plain and squealer Blade tips
    ASME Turbo Expo 2004: Power for Land Sea and Air, 2004
    Co-Authors: Hasan Nasir, Srinath V. Ekkad, Ronald Scott Bunker, Chander Prakash
    Abstract:

    The present study investigates the effect of orthogonal tip gap film injection from a plain and squealer tip of a HPT first stage rotor Blade. The pressure ratio (inlet total pressure to exit static pressure) for the cascade used was 1.2, and the experiments were run in a blow-down test rig with a four-Blade stationary linear cascade. The Reynolds number based on cascade exit velocity and axial chord length was 8.61×105 and the inlet and exit Mach numbers were 0.16 and 0.55, respectively. Five holes are located along the camber line of the Blade tip. A transient infrared technique was used to measure the local heat transfer coefficient and film effectiveness from a single transient test. All measurements were made for three blowing ratios of 1.0, 1.5, and 2.0. For all the cases, a small tip gap-to-Blade Span ratio of 0.5% was used. The squealer depth-to-Blade Span ratio of 4.16% was used for the squealer. Results show that the film injection has some effect for plain tips but has no effect or negligible effect for squealer tips.Copyright © 2004 by ASME

  • Effect of Tip Gap and Squealer Geometry on Measured Heat Transfer Over a HPT Rotor Blade Tip
    Heat Transfer Volume 2, 2003
    Co-Authors: Hasan Nasir, Srinath V. Ekkad, Ronald Scott Bunker, David Kontrovitz, Chander Prakash
    Abstract:

    The present study explores the effects of gap height and tip geometry on heat transfer distribution over the tip surface of a HPT first stage rotor Blade. The pressure ratio (inlet total pressure to exit static pressure for the cascade) used was 1.2, and the experiments were run in a blow-down test rig with a four-Blade linear cascade. A transient liquid crystal technique was used to obtain the tip heat transfer distributions. Pressure measurements were made on the Blade surface and on the shroud for different tip geometries and tip gaps to characterize the leakage flow and understand the heat transfer distributions. Two different tip gap-to-Blade Span ratio of 1% and 2.6% are investigated for a plane tip and a deep squealer with depth-to-Blade Span ratio of 0.0416. For a shallow squealer with depth-to-Blade Span ratio of 0.0104, only 1% gap-to-Span ratio is considered. The presence of the squealer alters the tip gap flow field significantly and produces lower overall heat transfer coefficients. The effects of different partial squealer arrangements are also investigated for the shallow squealer depth. These simulate partial burning off of the squealer in real turbine Blades. Results show that in some cases, partial burning of squealers along the pressure surface may be beneficial in terms of overall reduction in heat transfer coefficients over the tip surface compared to the plain tip.Copyright © 2003 by ASME

  • Numerical Simulation of Flow and Heat Transfer Past a Turbine Blade With a Squealer-Tip
    Volume 3: Turbo Expo 2002 Parts A and B, 2002
    Co-Authors: Huitao Yang, Srinath V. Ekkad, Chander Prakash, Sumanta Acharya, Ron Bunker
    Abstract:

    Numerical calculations are performed to simulate the tip leakage flow and heat transfer on the squealer (recessed) tip of GE-E3 turbine rotor Blade. A squealer tip with a 3.77% recess of the Blade Span is considered in this study, and the results are compared with the predictions for a flat-tip Blade. The calculations have been performed for an isothermal Blade with an overall pressure ratio of 1.32, an inlet turbulence intensity of 6.1%, and for three different tip gap clearances of 1%, 1.5% and 2.5% of the Blade Span. These conditions correspond to the experiments reported by Azad et al. [1]. The calculations have been performed for three different turbulence models (the standard high Re k-e model, the RNG k-e and the Reynolds Stress Model) in order to assess the capability of the models in correctly predicting the Blade heat transfer. The predictions show good agreement with the experimental data, with the Reynolds stress model calculations clearly providing the best results. Substantial reductions in the tip heat transfer and leakage flow is obtained with the squealer tip configuration. With the squealer tip, the heat transfer coefficients on the shroud and on the suction surface of the Blade are also considerably reduced.© 2002 ASME

Zhaofang Liu - One of the best experts on this subject based on the ideXlab platform.

  • Unsteady Analysis on the Effects of Tip Clearance Height on Hot Streak Migration Across Rotor Blade Tip Clearance
    Journal of Engineering for Gas Turbines and Power, 2014
    Co-Authors: Zhaofang Liu, Zhao Liu, Zhenping Feng
    Abstract:

    This paper presents an investigation on the hot streak migration across rotor Blade tip clearance in a high pressure gas turbine with different tip clearance heights. The Blade geometry is taken from the first stage of GE-E3 turbine engine. Three tip clearances, 1.0%, 1.5% and 2.5% of the Blade Span with a flat tip were investigated respectively, and the uniform and non-uniform inlet temperature profiles were taken as the inlet boundary conditions. By solving the unsteady compressible Reynolds-averaged Navier-Stokes equations, the time dependent solutions were obtained. The results indicate that the large tip clearance intensifies the leakage flow, increases the hot streak migration rate, and aggravates the heat transfer environment on Blade tip. However, the reverse secondary flow dominated by the relative motion of casing is insensitive to the change of tip clearance height. Attributed to the high-speed rotation of rotor Blade and the low pressure difference between both sides of Blade, a reverse leakage flow zone emerges over Blade tip near trailing edge. To eliminate the effects of Blade profile variation due to twist along the Blade Span on the aerothermal performance in tip clearance, the tested rotor (straight) Blade and the original rotor (twisted) Blade of GE-E3 first stage with the same tip profile are compared in this paper.Copyright © 2013 by ASME

  • Unsteady Analysis on the Effects of Tip Clearance Height on Hot Streak Migration Across Rotor Blade Tip Clearance
    Volume 6C: Turbomachinery, 2013
    Co-Authors: Zhaofang Liu, Zhao Liu, Zhenping Feng
    Abstract:

    This paper presents an investigation on the hot streak migration across rotor Blade tip clearance in a high pressure gas turbine with different tip clearance heights. The Blade geometry is taken from the first stage of GE-E3 turbine engine. Three tip clearances, 1.0%, 1.5% and 2.5% of the Blade Span with a flat tip were investigated respectively, and the uniform and non-uniform inlet temperature profiles were taken as the inlet boundary conditions. By solving the unsteady compressible Reynolds-averaged Navier-Stokes equations, the time dependent solutions were obtained. The results indicate that the large tip clearance intensifies the leakage flow, increases the hot streak migration rate, and aggravates the heat transfer environment on Blade tip. However, the reverse secondary flow dominated by the relative motion of casing is insensitive to the change of tip clearance height. Attributed to the high-speed rotation of rotor Blade and the low pressure difference between both sides of Blade, a reverse leakage flow zone emerges over Blade tip near trailing edge. To eliminate the effects of Blade profile variation due to twist along the Blade Span on the aerothermal performance in tip clearance, the tested rotor (straight) Blade and the original rotor (twisted) Blade of GE-E3 first stage with the same tip profile are compared in this paper.